Get dashboard metrics as JSON

Returns complete dashboard data including:

• Period information
• Visits metrics
• Customer metrics (loyal vs new)
• Referral metrics
• Loyalty ROI
• Transaction metrics
• Retention metrics

Integration access is restricted to the credential's location. Pagination, monetary units and response envelopes are endpoint-specific; use the schema below. Do not assume that POST/PATCH requests are safe to retry after a timeout.